1 /* 2 * hostapd / EAP-pwd (RFC 5931) server 3 * Copyright (c) 2010, Dan Harkins <dharkins (at) lounge.org> 4 * 5 * This software may be distributed under the terms of the BSD license. 6 * See README for more details. 7 */ 8 9 #include "includes.h" 10 11 #include "common.h" 12 #include "crypto/sha256.h" 13 #include "eap_server/eap_i.h" 14 #include "eap_common/eap_pwd_common.h" 15 16 17 struct eap_pwd_data { 18 enum { 19 PWD_ID_Req, PWD_Commit_Req, PWD_Confirm_Req, SUCCESS, FAILURE 20 } state; 21 u8 *id_peer; 22 size_t id_peer_len; 23 u8 *id_server; 24 size_t id_server_len; 25 u8 *password; 26 size_t password_len; 27 u32 token; 28 u16 group_num; 29 EAP_PWD_group *grp; 30 31 struct wpabuf *inbuf; 32 size_t in_frag_pos; 33 struct wpabuf *outbuf; 34 size_t out_frag_pos; 35 size_t mtu; 36 37 BIGNUM *k; 38 BIGNUM *private_value; 39 BIGNUM *peer_scalar; 40 BIGNUM *my_scalar; 41 EC_POINT *my_element; 42 EC_POINT *peer_element; 43 44 u8 my_confirm[SHA256_MAC_LEN]; 45 46 u8 msk[EAP_MSK_LEN]; 47 u8 emsk[EAP_EMSK_LEN]; 48 49 BN_CTX *bnctx; 50 }; 51 52 53 static const char * eap_pwd_state_txt(int state) 54 { 55 switch (state) { 56 case PWD_ID_Req: 57 return "PWD-ID-Req"; 58 case PWD_Commit_Req: 59 return "PWD-Commit-Req"; 60 case PWD_Confirm_Req: 61 return "PWD-Confirm-Req"; 62 case SUCCESS: 63 return "SUCCESS"; 64 case FAILURE: 65 return "FAILURE"; 66 default: 67 return "PWD-Unk"; 68 } 69 } 70 71 72 static void eap_pwd_state(struct eap_pwd_data *data, int state) 73 { 74 wpa_printf(MSG_DEBUG, "EAP-pwd: %s -> %s", 75 eap_pwd_state_txt(data->state), eap_pwd_state_txt(state)); 76 data->state = state; 77 } 78 79 80 static void * eap_pwd_init(struct eap_sm *sm) 81 { 82 struct eap_pwd_data *data; 83 84 if (sm->user == NULL || sm->user->password == NULL || 85 sm->user->password_len == 0) { 86 wpa_printf(MSG_INFO, "EAP-PWD (server): Password is not " 87 "configured"); 88 return NULL; 89 } 90 91 data = os_zalloc(sizeof(*data)); 92 if (data == NULL) 93 return NULL; 94 95 data->group_num = sm->pwd_group; 96 wpa_printf(MSG_DEBUG, "EAP-pwd: Selected group number %d", 97 data->group_num); 98 data->state = PWD_ID_Req; 99 100 data->id_server = (u8 *) os_strdup("server"); 101 if (data->id_server) 102 data->id_server_len = os_strlen((char *) data->id_server); 103 104 data->password = os_malloc(sm->user->password_len); 105 if (data->password == NULL) { 106 wpa_printf(MSG_INFO, "EAP-PWD: Memory allocation password " 107 "fail"); 108 os_free(data->id_server); 109 os_free(data); 110 return NULL; 111 } 112 data->password_len = sm->user->password_len; 113 os_memcpy(data->password, sm->user->password, data->password_len); 114 115 data->bnctx = BN_CTX_new(); 116 if (data->bnctx == NULL) { 117 wpa_printf(MSG_INFO, "EAP-PWD: bn context allocation fail"); 118 os_free(data->password); 119 os_free(data->id_server); 120 os_free(data); 121 return NULL; 122 } 123 124 data->in_frag_pos = data->out_frag_pos = 0; 125 data->inbuf = data->outbuf = NULL; 126 data->mtu = 1020; /* default from RFC 5931, make it configurable! */ 127 128 return data; 129 } 130 131 132 static void eap_pwd_reset(struct eap_sm *sm, void *priv) 133 { 134 struct eap_pwd_data *data = priv; 135 136 BN_free(data->private_value); 137 BN_free(data->peer_scalar); 138 BN_free(data->my_scalar); 139 BN_free(data->k); 140 BN_CTX_free(data->bnctx); 141 EC_POINT_free(data->my_element); 142 EC_POINT_free(data->peer_element); 143 os_free(data->id_peer); 144 os_free(data->id_server); 145 os_free(data->password); 146 if (data->grp) { 147 EC_GROUP_free(data->grp->group); 148 EC_POINT_free(data->grp->pwe); 149 BN_free(data->grp->order); 150 BN_free(data->grp->prime); 151 os_free(data->grp); 152 } 153 os_free(data); 154 } 155 156 157 static void eap_pwd_build_id_req(struct eap_sm *sm, struct eap_pwd_data *data, 158 u8 id) 159 { 160 wpa_printf(MSG_DEBUG, "EAP-pwd: ID/Request"); 161 /* 162 * if we're fragmenting then we already have an id request, just return 163 */ 164 if (data->out_frag_pos) 165 return; 166 167 data->outbuf = wpabuf_alloc(sizeof(struct eap_pwd_id) + 168 data->id_server_len); 169 if (data->outbuf == NULL) { 170 eap_pwd_state(data, FAILURE); 171 return; 172 } 173 174 /* an lfsr is good enough to generate unpredictable tokens */ 175 data->token = os_random(); 176 wpabuf_put_be16(data->outbuf, data->group_num); 177 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_RAND_FUNC); 178 wpabuf_put_u8(data->outbuf, EAP_PWD_DEFAULT_PRF); 179 wpabuf_put_data(data->outbuf, &data->token, sizeof(data->token)); 180 wpabuf_put_u8(data->outbuf, EAP_PWD_PREP_NONE); 181 wpabuf_put_data(data->outbuf, data->id_server, data->id_server_len); 182 } 183 184 185 static void eap_pwd_build_commit_req(struct eap_sm *sm, 186 struct eap_pwd_data *data, u8 id) 187 { 188 BIGNUM *mask = NULL, *x = NULL, *y = NULL; 189 u8 *scalar = NULL, *element = NULL; 190 u16 offset; 191 192 wpa_printf(MSG_DEBUG, "EAP-pwd: Commit/Request"); 193 /* 194 * if we're fragmenting then we already have an commit request, just 195 * return 196 */ 197 if (data->out_frag_pos) 198 return; 199 200 if (((data->private_value = BN_new()) == NULL) || 201 ((data->my_element = EC_POINT_new(data->grp->group)) == NULL) || 202 ((data->my_scalar = BN_new()) == NULL) || 203 ((mask = BN_new()) == NULL)) { 204 wpa_printf(MSG_INFO, "EAP-PWD (server): scalar allocation " 205 "fail"); 206 goto fin; 207 } 208 209 BN_rand_range(data->private_value, data->grp->order); 210 BN_rand_range(mask, data->grp->order); 211 BN_add(data->my_scalar, data->private_value, mask); 212 BN_mod(data->my_scalar, data->my_scalar, data->grp->order, 213 data->bnctx); 214 215 if (!EC_POINT_mul(data->grp->group, data->my_element, NULL, 216 data->grp->pwe, mask, data->bnctx)) { 217 wpa_printf(MSG_INFO, "EAP-PWD (server): element allocation " 218 "fail"); 219 eap_pwd_state(data, FAILURE); 220 goto fin; 221 } 222 223 if (!EC_POINT_invert(data->grp->group, data->my_element, data->bnctx)) 224 { 225 wpa_printf(MSG_INFO, "EAP-PWD (server): element inversion " 226 "fail"); 227 goto fin; 228 } 229 BN_free(mask); 230 231 if (((x = BN_new()) == NULL) || 232 ((y = BN_new()) == NULL)) { 233 wpa_printf(MSG_INFO, "EAP-PWD (server): point allocation " 234 "fail"); 235 goto fin; 236 } 237 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 238 data->my_element, x, y, 239 data->bnctx)) { 240 wpa_printf(MSG_INFO, "EAP-PWD (server): point assignment " 241 "fail"); 242 goto fin; 243 } 244 245 if (((scalar = os_malloc(BN_num_bytes(data->grp->order))) == NULL) || 246 ((element = os_malloc(BN_num_bytes(data->grp->prime) * 2)) == 247 NULL)) { 248 wpa_printf(MSG_INFO, "EAP-PWD (server): data allocation fail"); 249 goto fin; 250 } 251 252 /* 253 * bignums occupy as little memory as possible so one that is 254 * sufficiently smaller than the prime or order might need pre-pending 255 * with zeros. 256 */ 257 os_memset(scalar, 0, BN_num_bytes(data->grp->order)); 258 os_memset(element, 0, BN_num_bytes(data->grp->prime) * 2); 259 offset = BN_num_bytes(data->grp->order) - 260 BN_num_bytes(data->my_scalar); 261 BN_bn2bin(data->my_scalar, scalar + offset); 262 263 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 264 BN_bn2bin(x, element + offset); 265 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 266 BN_bn2bin(y, element + BN_num_bytes(data->grp->prime) + offset); 267 268 data->outbuf = wpabuf_alloc(2 * BN_num_bytes(data->grp->prime) + 269 BN_num_bytes(data->grp->order)); 270 if (data->outbuf == NULL) 271 goto fin; 272 273 /* We send the element as (x,y) followed by the scalar */ 274 wpabuf_put_data(data->outbuf, element, 275 2 * BN_num_bytes(data->grp->prime)); 276 wpabuf_put_data(data->outbuf, scalar, BN_num_bytes(data->grp->order)); 277 278 fin: 279 os_free(scalar); 280 os_free(element); 281 BN_free(x); 282 BN_free(y); 283 if (data->outbuf == NULL) 284 eap_pwd_state(data, FAILURE); 285 } 286 287 288 static void eap_pwd_build_confirm_req(struct eap_sm *sm, 289 struct eap_pwd_data *data, u8 id) 290 { 291 BIGNUM *x = NULL, *y = NULL; 292 struct crypto_hash *hash; 293 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 294 u16 grp; 295 int offset; 296 297 wpa_printf(MSG_DEBUG, "EAP-pwd: Confirm/Request"); 298 /* 299 * if we're fragmenting then we already have an confirm request, just 300 * return 301 */ 302 if (data->out_frag_pos) 303 return; 304 305 /* Each component of the cruft will be at most as big as the prime */ 306 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 307 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 308 wpa_printf(MSG_INFO, "EAP-PWD (server): debug allocation " 309 "fail"); 310 goto fin; 311 } 312 313 /* 314 * commit is H(k | server_element | server_scalar | peer_element | 315 * peer_scalar | ciphersuite) 316 */ 317 hash = eap_pwd_h_init(); 318 if (hash == NULL) 319 goto fin; 320 321 /* 322 * Zero the memory each time because this is mod prime math and some 323 * value may start with a few zeros and the previous one did not. 324 * 325 * First is k 326 */ 327 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 328 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 329 BN_bn2bin(data->k, cruft + offset); 330 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 331 332 /* server element: x, y */ 333 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 334 data->my_element, x, y, 335 data->bnctx)) { 336 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 337 "assignment fail"); 338 goto fin; 339 } 340 341 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 342 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 343 BN_bn2bin(x, cruft + offset); 344 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 345 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 346 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 347 BN_bn2bin(y, cruft + offset); 348 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 349 350 /* server scalar */ 351 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 352 offset = BN_num_bytes(data->grp->order) - 353 BN_num_bytes(data->my_scalar); 354 BN_bn2bin(data->my_scalar, cruft + offset); 355 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 356 357 /* peer element: x, y */ 358 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 359 data->peer_element, x, y, 360 data->bnctx)) { 361 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 362 "assignment fail"); 363 goto fin; 364 } 365 366 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 367 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 368 BN_bn2bin(x, cruft + offset); 369 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 370 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 371 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 372 BN_bn2bin(y, cruft + offset); 373 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 374 375 /* peer scalar */ 376 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 377 offset = BN_num_bytes(data->grp->order) - 378 BN_num_bytes(data->peer_scalar); 379 BN_bn2bin(data->peer_scalar, cruft + offset); 380 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 381 382 /* ciphersuite */ 383 grp = htons(data->group_num); 384 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 385 ptr = cruft; 386 os_memcpy(ptr, &grp, sizeof(u16)); 387 ptr += sizeof(u16); 388 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 389 ptr += sizeof(u8); 390 *ptr = EAP_PWD_DEFAULT_PRF; 391 ptr += sizeof(u8); 392 eap_pwd_h_update(hash, cruft, ptr - cruft); 393 394 /* all done with the random function */ 395 eap_pwd_h_final(hash, conf); 396 os_memcpy(data->my_confirm, conf, SHA256_MAC_LEN); 397 398 data->outbuf = wpabuf_alloc(SHA256_MAC_LEN); 399 if (data->outbuf == NULL) 400 goto fin; 401 402 wpabuf_put_data(data->outbuf, conf, SHA256_MAC_LEN); 403 404 fin: 405 os_free(cruft); 406 BN_free(x); 407 BN_free(y); 408 if (data->outbuf == NULL) 409 eap_pwd_state(data, FAILURE); 410 } 411 412 413 static struct wpabuf * 414 eap_pwd_build_req(struct eap_sm *sm, void *priv, u8 id) 415 { 416 struct eap_pwd_data *data = priv; 417 struct wpabuf *req; 418 u8 lm_exch; 419 const u8 *buf; 420 u16 totlen = 0; 421 size_t len; 422 423 /* 424 * if we're buffering response fragments then just ACK 425 */ 426 if (data->in_frag_pos) { 427 wpa_printf(MSG_DEBUG, "EAP-pwd: ACKing a fragment!!"); 428 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 429 EAP_PWD_HDR_SIZE, EAP_CODE_REQUEST, id); 430 if (req == NULL) { 431 eap_pwd_state(data, FAILURE); 432 return NULL; 433 } 434 switch (data->state) { 435 case PWD_ID_Req: 436 wpabuf_put_u8(req, EAP_PWD_OPCODE_ID_EXCH); 437 break; 438 case PWD_Commit_Req: 439 wpabuf_put_u8(req, EAP_PWD_OPCODE_COMMIT_EXCH); 440 break; 441 case PWD_Confirm_Req: 442 wpabuf_put_u8(req, EAP_PWD_OPCODE_CONFIRM_EXCH); 443 break; 444 default: 445 eap_pwd_state(data, FAILURE); /* just to be sure */ 446 wpabuf_free(req); 447 return NULL; 448 } 449 return req; 450 } 451 452 /* 453 * build the data portion of a request 454 */ 455 switch (data->state) { 456 case PWD_ID_Req: 457 eap_pwd_build_id_req(sm, data, id); 458 lm_exch = EAP_PWD_OPCODE_ID_EXCH; 459 break; 460 case PWD_Commit_Req: 461 eap_pwd_build_commit_req(sm, data, id); 462 lm_exch = EAP_PWD_OPCODE_COMMIT_EXCH; 463 break; 464 case PWD_Confirm_Req: 465 eap_pwd_build_confirm_req(sm, data, id); 466 lm_exch = EAP_PWD_OPCODE_CONFIRM_EXCH; 467 break; 468 default: 469 wpa_printf(MSG_INFO, "EAP-pwd: Unknown state %d in build_req", 470 data->state); 471 eap_pwd_state(data, FAILURE); 472 lm_exch = 0; /* hush now, sweet compiler */ 473 break; 474 } 475 476 if (data->state == FAILURE) 477 return NULL; 478 479 /* 480 * determine whether that data needs to be fragmented 481 */ 482 len = wpabuf_len(data->outbuf) - data->out_frag_pos; 483 if ((len + EAP_PWD_HDR_SIZE) > data->mtu) { 484 len = data->mtu - EAP_PWD_HDR_SIZE; 485 EAP_PWD_SET_MORE_BIT(lm_exch); 486 /* 487 * if this is the first fragment, need to set the M bit 488 * and add the total length to the eap_pwd_hdr 489 */ 490 if (data->out_frag_pos == 0) { 491 EAP_PWD_SET_LENGTH_BIT(lm_exch); 492 totlen = wpabuf_len(data->outbuf) + 493 EAP_PWD_HDR_SIZE + sizeof(u16); 494 len -= sizeof(u16); 495 wpa_printf(MSG_DEBUG, "EAP-pwd: Fragmenting output, " 496 "total length = %d", totlen); 497 } 498 wpa_printf(MSG_DEBUG, "EAP-pwd: Send a %d byte fragment", 499 (int) len); 500 } 501 502 /* 503 * alloc an eap request and populate it with the data 504 */ 505 req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PWD, 506 EAP_PWD_HDR_SIZE + len + 507 (totlen ? sizeof(u16) : 0), 508 EAP_CODE_REQUEST, id); 509 if (req == NULL) { 510 eap_pwd_state(data, FAILURE); 511 return NULL; 512 } 513 514 wpabuf_put_u8(req, lm_exch); 515 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) 516 wpabuf_put_be16(req, totlen); 517 518 buf = wpabuf_head_u8(data->outbuf); 519 wpabuf_put_data(req, buf + data->out_frag_pos, len); 520 data->out_frag_pos += len; 521 /* 522 * either not fragged or last fragment, either way free up the data 523 */ 524 if (data->out_frag_pos >= wpabuf_len(data->outbuf)) { 525 wpabuf_free(data->outbuf); 526 data->out_frag_pos = 0; 527 } 528 529 return req; 530 } 531 532 533 static Boolean eap_pwd_check(struct eap_sm *sm, void *priv, 534 struct wpabuf *respData) 535 { 536 struct eap_pwd_data *data = priv; 537 const u8 *pos; 538 size_t len; 539 540 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 541 if (pos == NULL || len < 1) { 542 wpa_printf(MSG_INFO, "EAP-pwd: Invalid frame"); 543 return TRUE; 544 } 545 546 wpa_printf(MSG_DEBUG, "EAP-pwd: Received frame: exch = %d, len = %d", 547 EAP_PWD_GET_EXCHANGE(*pos), (int) len); 548 549 if (data->state == PWD_ID_Req && 550 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_ID_EXCH)) 551 return FALSE; 552 553 if (data->state == PWD_Commit_Req && 554 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_COMMIT_EXCH)) 555 return FALSE; 556 557 if (data->state == PWD_Confirm_Req && 558 ((EAP_PWD_GET_EXCHANGE(*pos)) == EAP_PWD_OPCODE_CONFIRM_EXCH)) 559 return FALSE; 560 561 wpa_printf(MSG_INFO, "EAP-pwd: Unexpected opcode=%d in state=%d", 562 *pos, data->state); 563 564 return TRUE; 565 } 566 567 568 static void eap_pwd_process_id_resp(struct eap_sm *sm, 569 struct eap_pwd_data *data, 570 const u8 *payload, size_t payload_len) 571 { 572 struct eap_pwd_id *id; 573 574 if (payload_len < sizeof(struct eap_pwd_id)) { 575 wpa_printf(MSG_INFO, "EAP-pwd: Invalid ID response"); 576 return; 577 } 578 579 id = (struct eap_pwd_id *) payload; 580 if ((data->group_num != be_to_host16(id->group_num)) || 581 (id->random_function != EAP_PWD_DEFAULT_RAND_FUNC) || 582 (os_memcmp(id->token, (u8 *)&data->token, sizeof(data->token))) || 583 (id->prf != EAP_PWD_DEFAULT_PRF)) { 584 wpa_printf(MSG_INFO, "EAP-pwd: peer changed parameters"); 585 eap_pwd_state(data, FAILURE); 586 return; 587 } 588 data->id_peer = os_malloc(payload_len - sizeof(struct eap_pwd_id)); 589 if (data->id_peer == NULL) { 590 wpa_printf(MSG_INFO, "EAP-PWD: memory allocation id fail"); 591 return; 592 } 593 data->id_peer_len = payload_len - sizeof(struct eap_pwd_id); 594 os_memcpy(data->id_peer, id->identity, data->id_peer_len); 595 wpa_hexdump_ascii(MSG_DEBUG, "EAP-PWD (server): peer sent id of", 596 data->id_peer, data->id_peer_len); 597 598 if ((data->grp = os_malloc(sizeof(EAP_PWD_group))) == NULL) { 599 wpa_printf(MSG_INFO, "EAP-PWD: failed to allocate memory for " 600 "group"); 601 return; 602 } 603 if (compute_password_element(data->grp, data->group_num, 604 data->password, data->password_len, 605 data->id_server, data->id_server_len, 606 data->id_peer, data->id_peer_len, 607 (u8 *) &data->token)) { 608 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to compute " 609 "PWE"); 610 return; 611 } 612 wpa_printf(MSG_DEBUG, "EAP-PWD (server): computed %d bit PWE...", 613 BN_num_bits(data->grp->prime)); 614 615 eap_pwd_state(data, PWD_Commit_Req); 616 } 617 618 619 static void 620 eap_pwd_process_commit_resp(struct eap_sm *sm, struct eap_pwd_data *data, 621 const u8 *payload, size_t payload_len) 622 { 623 u8 *ptr; 624 BIGNUM *x = NULL, *y = NULL, *cofactor = NULL; 625 EC_POINT *K = NULL, *point = NULL; 626 int res = 0; 627 628 wpa_printf(MSG_DEBUG, "EAP-pwd: Received commit response"); 629 630 if (((data->peer_scalar = BN_new()) == NULL) || 631 ((data->k = BN_new()) == NULL) || 632 ((cofactor = BN_new()) == NULL) || 633 ((x = BN_new()) == NULL) || 634 ((y = BN_new()) == NULL) || 635 ((point = EC_POINT_new(data->grp->group)) == NULL) || 636 ((K = EC_POINT_new(data->grp->group)) == NULL) || 637 ((data->peer_element = EC_POINT_new(data->grp->group)) == NULL)) { 638 wpa_printf(MSG_INFO, "EAP-PWD (server): peer data allocation " 639 "fail"); 640 goto fin; 641 } 642 643 if (!EC_GROUP_get_cofactor(data->grp->group, cofactor, NULL)) { 644 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to get " 645 "cofactor for curve"); 646 goto fin; 647 } 648 649 /* element, x then y, followed by scalar */ 650 ptr = (u8 *) payload; 651 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), x); 652 ptr += BN_num_bytes(data->grp->prime); 653 BN_bin2bn(ptr, BN_num_bytes(data->grp->prime), y); 654 ptr += BN_num_bytes(data->grp->prime); 655 BN_bin2bn(ptr, BN_num_bytes(data->grp->order), data->peer_scalar); 656 if (!EC_POINT_set_affine_coordinates_GFp(data->grp->group, 657 data->peer_element, x, y, 658 data->bnctx)) { 659 wpa_printf(MSG_INFO, "EAP-PWD (server): setting peer element " 660 "fail"); 661 goto fin; 662 } 663 664 /* check to ensure peer's element is not in a small sub-group */ 665 if (BN_cmp(cofactor, BN_value_one())) { 666 if (!EC_POINT_mul(data->grp->group, point, NULL, 667 data->peer_element, cofactor, NULL)) { 668 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 669 "multiply peer element by order"); 670 goto fin; 671 } 672 if (EC_POINT_is_at_infinity(data->grp->group, point)) { 673 wpa_printf(MSG_INFO, "EAP-PWD (server): peer element " 674 "is at infinity!\n"); 675 goto fin; 676 } 677 } 678 679 /* compute the shared key, k */ 680 if ((!EC_POINT_mul(data->grp->group, K, NULL, data->grp->pwe, 681 data->peer_scalar, data->bnctx)) || 682 (!EC_POINT_add(data->grp->group, K, K, data->peer_element, 683 data->bnctx)) || 684 (!EC_POINT_mul(data->grp->group, K, NULL, K, data->private_value, 685 data->bnctx))) { 686 wpa_printf(MSG_INFO, "EAP-PWD (server): computing shared key " 687 "fail"); 688 goto fin; 689 } 690 691 /* ensure that the shared key isn't in a small sub-group */ 692 if (BN_cmp(cofactor, BN_value_one())) { 693 if (!EC_POINT_mul(data->grp->group, K, NULL, K, cofactor, 694 NULL)) { 695 wpa_printf(MSG_INFO, "EAP-PWD (server): cannot " 696 "multiply shared key point by order!\n"); 697 goto fin; 698 } 699 } 700 701 /* 702 * This check is strictly speaking just for the case above where 703 * co-factor > 1 but it was suggested that even though this is probably 704 * never going to happen it is a simple and safe check "just to be 705 * sure" so let's be safe. 706 */ 707 if (EC_POINT_is_at_infinity(data->grp->group, K)) { 708 wpa_printf(MSG_INFO, "EAP-PWD (server): shared key point is " 709 "at infinity"); 710 goto fin; 711 } 712 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, K, data->k, 713 NULL, data->bnctx)) { 714 wpa_printf(MSG_INFO, "EAP-PWD (server): unable to extract " 715 "shared secret from secret point"); 716 goto fin; 717 } 718 res = 1; 719 720 fin: 721 EC_POINT_free(K); 722 EC_POINT_free(point); 723 BN_free(cofactor); 724 BN_free(x); 725 BN_free(y); 726 727 if (res) 728 eap_pwd_state(data, PWD_Confirm_Req); 729 else 730 eap_pwd_state(data, FAILURE); 731 } 732 733 734 static void 735 eap_pwd_process_confirm_resp(struct eap_sm *sm, struct eap_pwd_data *data, 736 const u8 *payload, size_t payload_len) 737 { 738 BIGNUM *x = NULL, *y = NULL; 739 struct crypto_hash *hash; 740 u32 cs; 741 u16 grp; 742 u8 conf[SHA256_MAC_LEN], *cruft = NULL, *ptr; 743 int offset; 744 745 /* build up the ciphersuite: group | random_function | prf */ 746 grp = htons(data->group_num); 747 ptr = (u8 *) &cs; 748 os_memcpy(ptr, &grp, sizeof(u16)); 749 ptr += sizeof(u16); 750 *ptr = EAP_PWD_DEFAULT_RAND_FUNC; 751 ptr += sizeof(u8); 752 *ptr = EAP_PWD_DEFAULT_PRF; 753 754 /* each component of the cruft will be at most as big as the prime */ 755 if (((cruft = os_malloc(BN_num_bytes(data->grp->prime))) == NULL) || 756 ((x = BN_new()) == NULL) || ((y = BN_new()) == NULL)) { 757 wpa_printf(MSG_INFO, "EAP-PWD (peer): allocation fail"); 758 goto fin; 759 } 760 761 /* 762 * commit is H(k | peer_element | peer_scalar | server_element | 763 * server_scalar | ciphersuite) 764 */ 765 hash = eap_pwd_h_init(); 766 if (hash == NULL) 767 goto fin; 768 769 /* k */ 770 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 771 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(data->k); 772 BN_bn2bin(data->k, cruft + offset); 773 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 774 775 /* peer element: x, y */ 776 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 777 data->peer_element, x, y, 778 data->bnctx)) { 779 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 780 "assignment fail"); 781 goto fin; 782 } 783 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 784 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 785 BN_bn2bin(x, cruft + offset); 786 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 787 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 788 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 789 BN_bn2bin(y, cruft + offset); 790 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 791 792 /* peer scalar */ 793 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 794 offset = BN_num_bytes(data->grp->order) - 795 BN_num_bytes(data->peer_scalar); 796 BN_bn2bin(data->peer_scalar, cruft + offset); 797 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 798 799 /* server element: x, y */ 800 if (!EC_POINT_get_affine_coordinates_GFp(data->grp->group, 801 data->my_element, x, y, 802 data->bnctx)) { 803 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm point " 804 "assignment fail"); 805 goto fin; 806 } 807 808 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 809 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(x); 810 BN_bn2bin(x, cruft + offset); 811 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 812 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 813 offset = BN_num_bytes(data->grp->prime) - BN_num_bytes(y); 814 BN_bn2bin(y, cruft + offset); 815 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->prime)); 816 817 /* server scalar */ 818 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 819 offset = BN_num_bytes(data->grp->order) - 820 BN_num_bytes(data->my_scalar); 821 BN_bn2bin(data->my_scalar, cruft + offset); 822 eap_pwd_h_update(hash, cruft, BN_num_bytes(data->grp->order)); 823 824 /* ciphersuite */ 825 os_memset(cruft, 0, BN_num_bytes(data->grp->prime)); 826 eap_pwd_h_update(hash, (u8 *) &cs, sizeof(u32)); 827 828 /* all done */ 829 eap_pwd_h_final(hash, conf); 830 831 ptr = (u8 *) payload; 832 if (os_memcmp(conf, ptr, SHA256_MAC_LEN)) { 833 wpa_printf(MSG_INFO, "EAP-PWD (server): confirm did not " 834 "verify"); 835 goto fin; 836 } 837 838 wpa_printf(MSG_DEBUG, "EAP-pwd (server): confirm verified"); 839 if (compute_keys(data->grp, data->bnctx, data->k, 840 data->peer_scalar, data->my_scalar, conf, 841 data->my_confirm, &cs, data->msk, data->emsk) < 0) 842 eap_pwd_state(data, FAILURE); 843 else 844 eap_pwd_state(data, SUCCESS); 845 846 fin: 847 os_free(cruft); 848 BN_free(x); 849 BN_free(y); 850 } 851 852 853 static void eap_pwd_process(struct eap_sm *sm, void *priv, 854 struct wpabuf *respData) 855 { 856 struct eap_pwd_data *data = priv; 857 const u8 *pos; 858 size_t len; 859 u8 lm_exch; 860 u16 tot_len; 861 862 pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_PWD, respData, &len); 863 if ((pos == NULL) || (len < 1)) { 864 wpa_printf(MSG_INFO, "Bad EAP header! pos %s and len = %d", 865 (pos == NULL) ? "is NULL" : "is not NULL", 866 (int) len); 867 return; 868 } 869 870 lm_exch = *pos; 871 pos++; /* skip over the bits and the exch */ 872 len--; 873 874 /* 875 * if we're fragmenting then this should be an ACK with no data, 876 * just return and continue fragmenting in the "build" section above 877 */ 878 if (data->out_frag_pos) { 879 if (len > 1) 880 wpa_printf(MSG_INFO, "EAP-pwd: Bad response! " 881 "Fragmenting but not an ACK"); 882 else 883 wpa_printf(MSG_DEBUG, "EAP-pwd: received ACK from " 884 "peer"); 885 return; 886 } 887 /* 888 * if we're receiving fragmented packets then we need to buffer... 889 * 890 * the first fragment has a total length 891 */ 892 if (EAP_PWD_GET_LENGTH_BIT(lm_exch)) { 893 tot_len = WPA_GET_BE16(pos); 894 wpa_printf(MSG_DEBUG, "EAP-pwd: Incoming fragments, total " 895 "length = %d", tot_len); 896 data->inbuf = wpabuf_alloc(tot_len); 897 if (data->inbuf == NULL) { 898 wpa_printf(MSG_INFO, "EAP-pwd: Out of memory to " 899 "buffer fragments!"); 900 return; 901 } 902 pos += sizeof(u16); 903 len -= sizeof(u16); 904 } 905 /* 906 * the first and all intermediate fragments have the M bit set 907 */ 908 if (EAP_PWD_GET_MORE_BIT(lm_exch)) { 909 if ((data->in_frag_pos + len) > wpabuf_size(data->inbuf)) { 910 wpa_printf(MSG_DEBUG, "EAP-pwd: Buffer overflow " 911 "attack detected! (%d+%d > %d)", 912 (int) data->in_frag_pos, (int) len, 913 (int) wpabuf_size(data->inbuf)); 914 eap_pwd_state(data, FAILURE); 915 return; 916 } 917 wpabuf_put_data(data->inbuf, pos, len); 918 data->in_frag_pos += len; 919 wpa_printf(MSG_DEBUG, "EAP-pwd: Got a %d byte fragment", 920 (int) len); 921 return; 922 } 923 /* 924 * last fragment won't have the M bit set (but we're obviously 925 * buffering fragments so that's how we know it's the last) 926 */ 927 if (data->in_frag_pos) { 928 wpabuf_put_data(data->inbuf, pos, len); 929 data->in_frag_pos += len; 930 pos = wpabuf_head_u8(data->inbuf); 931 len = data->in_frag_pos; 932 wpa_printf(MSG_DEBUG, "EAP-pwd: Last fragment, %d bytes", 933 (int) len); 934 } 935 switch (EAP_PWD_GET_EXCHANGE(lm_exch)) { 936 case EAP_PWD_OPCODE_ID_EXCH: 937 eap_pwd_process_id_resp(sm, data, pos, len); 938 break; 939 case EAP_PWD_OPCODE_COMMIT_EXCH: 940 eap_pwd_process_commit_resp(sm, data, pos, len); 941 break; 942 case EAP_PWD_OPCODE_CONFIRM_EXCH: 943 eap_pwd_process_confirm_resp(sm, data, pos, len); 944 break; 945 } 946 /* 947 * if we had been buffering fragments, here's a great place 948 * to clean up 949 */ 950 if (data->in_frag_pos) { 951 wpabuf_free(data->inbuf); 952 data->in_frag_pos = 0; 953 } 954 } 955 956 957 static u8 * eap_pwd_getkey(struct eap_sm *sm, void *priv, size_t *len) 958 { 959 struct eap_pwd_data *data = priv; 960 u8 *key; 961 962 if (data->state != SUCCESS) 963 return NULL; 964 965 key = os_malloc(EAP_MSK_LEN); 966 if (key == NULL) 967 return NULL; 968 969 os_memcpy(key, data->msk, EAP_MSK_LEN); 970 *len = EAP_MSK_LEN; 971 972 return key; 973 } 974 975 976 static u8 * eap_pwd_get_emsk(struct eap_sm *sm, void *priv, size_t *len) 977 { 978 struct eap_pwd_data *data = priv; 979 u8 *key; 980 981 if (data->state != SUCCESS) 982 return NULL; 983 984 key = os_malloc(EAP_EMSK_LEN); 985 if (key == NULL) 986 return NULL; 987 988 os_memcpy(key, data->emsk, EAP_EMSK_LEN); 989 *len = EAP_EMSK_LEN; 990 991 return key; 992 } 993 994 995 static Boolean eap_pwd_is_success(struct eap_sm *sm, void *priv) 996 { 997 struct eap_pwd_data *data = priv; 998 return data->state == SUCCESS; 999 } 1000 1001 1002 static Boolean eap_pwd_is_done(struct eap_sm *sm, void *priv) 1003 { 1004 struct eap_pwd_data *data = priv; 1005 return (data->state == SUCCESS) || (data->state == FAILURE); 1006 } 1007 1008 1009 int eap_server_pwd_register(void) 1010 { 1011 struct eap_method *eap; 1012 int ret; 1013 struct timeval tp; 1014 struct timezone tz; 1015 u32 sr; 1016 1017 EVP_add_digest(EVP_sha256()); 1018 1019 sr = 0xdeaddada; 1020 (void) gettimeofday(&tp, &tz); 1021 sr ^= (tp.tv_sec ^ tp.tv_usec); 1022 srandom(sr); 1023 1024 eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION, 1025 EAP_VENDOR_IETF, EAP_TYPE_PWD, 1026 "PWD"); 1027 if (eap == NULL) 1028 return -1; 1029 1030 eap->init = eap_pwd_init; 1031 eap->reset = eap_pwd_reset; 1032 eap->buildReq = eap_pwd_build_req; 1033 eap->check = eap_pwd_check; 1034 eap->process = eap_pwd_process; 1035 eap->isDone = eap_pwd_is_done; 1036 eap->getKey = eap_pwd_getkey; 1037 eap->get_emsk = eap_pwd_get_emsk; 1038 eap->isSuccess = eap_pwd_is_success; 1039 1040 ret = eap_server_method_register(eap); 1041 if (ret) 1042 eap_server_method_free(eap); 1043 return ret; 1044 } 1045 1046
